Using the Model of Hysteresis to Calculate the Precise Irrigation Rate for Silt Loam

The water-retention capacity of the soil is the most important hydrophysical property. It is formulated as the dependence between the volumetric water content of the soil and the capillary pressure of soil moisture. This study presents three models of the hysteretic water-retention capacity. The identification of the parameters was carried out by means of a point approximation of a measured data from the Mualem catalog on the main (boundary) drying and wetting branches of the silt loam using the original computer program «Soil-Hysteresis». A comparative analysis of hysteresis models is carried out on the basis of identifying significant differences between the errors of point approximation of measured data using the Williams–Kloot criterion. The advantages of the models improved by introducing an additional additive parameter are revealed. Applying the condition of equality of the exponential parameter values for drying and wetting branches eliminates the undesirable (methodical) «pump effect». The use of physically based models of hysteretic water-retention capacity has prospects for development and application of resource-saving technologies in precision irrigation farming.